The white plane happened to me when I was staring the game or returning to the game from desktop with Alt + Tab in Windows 10. Rasmus than changed it's colour to black. It's interesting that Windows saves that black plane instead or game screen for you. I haven't got any issues with Prt Scr or Alt + Prt Scr, got normal image from the game. I also wonder if that have something to do with using two monitors.

I think we're running on different platforms. I'm noticing this on both Windows 7 (PC with dual monitors) and Windows 8.1 (Laptop with single monitor). I just use the Alt option on Windowed Mode or when using the dual monitors so I don't get extra data. The PrtScr is also generating the same behavior.

The issue came back for you at the same time as I fixed the flickering Sebt pointed out when going into fullscreen. I fixed the flickering by drawing a black background in the window. And now you get a black screenshot... So I fixed this issue by only drawing the black background when going fullscreen.

Yeah, I found a issue with laptops that have two graphic cards. If the low end graphic card manages windows, then we can't use borderless fullscreen on the high end graphic card. It's weird, perhaps I will come up with an solution soon.
But it still don't work with print screen in real full screen for you Mello? (Just needs to be sure )

Yeah It just gives me a black screen at the size of resolution my game screen is set to if I use a true full screen mode. I guess I need to break out the old laptop I have that has a secondary video card to use as a test bed as well. I think that's where these types of issues showed up to begin with anyways.